Submultiple frequency generator



patented Jan.

SUBMULTIPLE FREQUENCY GENERATOR Ralph L. Miller, Montclair, N. J., assignor to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application July 5, 1934, Serial No. 733,791 4 Claims. (01. 250-36) This invention relates to the art of wave gen- 'eration and particularly to a method of or means for generating a, wave, the principal frequency of which has an, integral submultiple' (subharmonic) relation to a given, frequency. Accordingly the invention may, in one aspect, be considered as relating to a method of or means for subdividing a given frequency. 7

It is an object of the invention to produce a submultiple frequency wave by a method permitting the control of a greater amount of power than by prior alternative methods. The invention has its basis in the type of circult, or principle of operation, that has been i1- lustrated in practice as a means of producing an angular wave, that is, a square topped wave or a saw-toothed wave, depending on the precise relation of circuit elements. In general this prototype circuit is distinguished by the absence of a resonant circuit, comprising a combination of reactance elements of opposite signs, which has been commonly used in the generation of a wave by circuits involving electron discharge devices. Specifically it utilizes the principle of charging a condenser from a direct current source through an impedance and cyclically interrupting said charge and consequently discharging the condenser. The cyclical charge tends tobe automatically initiated at the completion of the discharge. A specific object of the invention is to improve a wave generator of the typeimmediately above described so as to permit of the use of a relatively large current during the charge and discharge periods and to further adapt it to be readily coerced by an impressed wave to insure an accurate correspondence between the two frequencies concerned, that is the frequency of the impressed series relationship, that is, with the anodes connected to therespective terminals of thecondenser andthe cathodes connected together. A charging source is connected betweenthe cathodes of thetwo tubes and the midpoint of the shunting resistance. The coercing wave, that is the control wave, is adapted to be impressed differentially on the control electrodes of the two tubes"... 7

With a circuit arranged as above, the condenser will tend cyclically to be charged through half of the resistance and the anode-cathode circuit of one of the tubes (the two tubes alternating in this function) and tobe abruptly discharged through the two tubes in series and'through the resistance. The discharge occurs when the condenser has charged to such a potential as to condition the tube which is then non-conducting to make it conducting by the impression of a superthresholdvalue of the control electrode potential corresponding to a peak value of the impressed wave. When this condition has been achieved, both tubes will have become conducting and, by the eiTective reorganization of the circuit thereby, theelectromotive force from the charging source as measured at the condenser is reduced to nearly zero, permitting the condenser to discharge. The discharge of the condenser reflexively interrupts the .circuit through the tube thus involved in the charging operation and makes the other tube conductive in turn, so that the'charge and discharge cycle is repeated with a reversal of the roles of the two tubes.

g In a sense the tubes function as'commutating means to cyclically condition the related circuit to charge and discharge the condenser. However, the circuit may perhaps best be thought of as comprising a Wheatstone bridge of which two legs consist of the two tubes and the other two legs consist of the two halves of the resistance, the direct current source and the condenser being bridged across individual pairs of diagonally opposite corners. When the bridge is balanced, as when both tubes conduct, the source and condenser are conjugate. Under this condition not only can the source no longer charge the condenser, but since the electromotive force impressed across the condenser becomes substantially zero, the condenser can discharge through the two resistances. At the other times the bridge is distorted, or unbalanced, by the effective elimination of one of the four legs, namely one of the tubes, so that there is no longer a conjugacy to prevent the condenser from being charged or to provide a means for its discharge.

For a more detaileddescription of the invention, reference may be had to the accompanying drawing forming part of the specification and the single figure of which illustrates one embodiment of the circuit of the invention.

The circuit comprises an input transformer l, three-electrode gas-filled space-discharge tubes 2 and 3, a condenser 4, and equal output resistances 5 and 6; A grid bias battery 1 delivering cathodes connected together and their anodes connected to the respective terminals of said condenser, a charging source connecting said cathodes in common with the junction point of said resistances, common biasing means for the control electrodes of said tubes, means impressing an alternating potential the frequency of which is to be changed difierentially on said control electrode, and an output circuit for the changed frequency potential connected across 10 said condenser.

RALPH L. MILLER.

M. NAEDER Jan. 21, 1936.,

' WELDING Filed. March 14, 1955 

